The Trends Dashboard, located at YouTube.com/TrendsDashboard, lets you see which videos are trending in a specific demographic, with the ability to sort by location (US state or country), age group, and sex. You can also do side-by-side comparisons of up to three different demographics.
There's also a YouTube Trends blog that shows you currently trending videos. It picks out four new videos at 4am and 4pm every day and also offers contextual explorations of videos, trends, and cultural phenomenon using YouTube's own internal data. YouTube Trends will also have billboard-style charts, data visualizations, and features highlighting what the YouTube ecosystem can tell us about major events as they unfold.